In active depth sensing, a projector projects patterns of light such as infrared (IR) dots to illuminate a region being sensed. The projected patterns are captured by a camera/sensor (two or more in stereo systems), with the image (or images) processed to compute a depth map or the like, e.g., per frame.
In stereo systems, stereo cameras capture two images from different viewpoints. Then, for example, one way to perform depth estimation with a stereo pair of images is to find correspondences between the images, e.g., to correlate intensity variations due to natural texture in one image with intensity variations in the other image.
However, existing depth systems/devices suffer from a number of drawbacks. Some systems use passive depth sensing, which is less accurate than active depth sensing. Some systems require that the projector be calibrated so that the exact pattern is generally known, which means if another such device is present, or if the laser pattern shifts (such as due to temperature), the device is unable to function properly. Other systems do not work in environments where ambient light overwhelms the projected light.